Underground reservoir for the storage of liquefied gases



Jan. 18, 1949. A. N. KERR 2,459,227

UNDERGROUND RESERVOIR FOR THE STORAGE 0F LIQUEFIED GASES Filed Aug. 6,1946 27 26 igwrg! l' f /fvvew ron. ANKERR By /Mq W ATTORNEYS .PatentedJan. 18, 1949 UNDERGROUND RESERVOIR FOR THE STORAGE OF LIQUEFIED GASESArthur N. Kerr, Los Angeles, Calif., assignor to Phillips PetroleumCompany, a corporation of Delaware Application August 6, 1946, SerialNo. 688,761

(Cl. (i2- 1) 4 Claims.

This invention relates to the storage of hydrocarbons. In one generalmodication this invention relates to the storage of hydrocarbons asliquids under a substantial`y superatmospheric pressure. In a preferredembodiment the invention relates to the storage of a liqueable normallygaseous hydrocarbon, such as propane.

Liqueable normally gaseous hydrocarbons, particularly propane and/orbutanes, are used in large quantities as fuels for domestic andindustrial" purposes, being generally referred to under the termliquefied petroleum gas. These materials are generally used in largequantities during the Winter months and in much smaller quantitiesduring the summer months. However, the supply of these materials isrelatively constant throughout the year. As a result there is a greatover-supply from about the middle of March until about September orOctober. By about the middle or last of December the demand has greatlyexceeded the current supply and there is often a pronounced shortage.

Although spherical tanks of substantial capacities are now availablecommercially in which butanes will be stored as liquids, it is oftennecessary to employ large numbers of such tanks, since the size of anyone tank is limited to about 10.000 barrels. Because propane has a muchhigher vapor pressure at ordinary atmospheric temperatures, it ispossible to store this material only in relatively small, heavy, andtherefore, expensive, tanks. Large bulk storage of propane is thereforenot possible economically.

It is an object of this invention to provide bulk storage of liquidhydrocarbons.

Another object of this invention is to store normally gaseoushydrocarbons in large quantities as liquids.

Still another object of this invention is to store propane as a liquidin large quantities Without constructing numerous high-pressure tanks.

Further objects and advantages of my invention will become apparent, toone skilled in the art, from the accompanying disclosure and discussion.

I have now found Athat it is possible to store -a liquid hydrocarbonmaterial under a substantial superatmospheric pressure in a single largestorage zone by excavating a large storage zone deep in the earth,lining this storage zone with a relatively thin lining which isimpervious to the liquid hydrocarbon being stored, and which is alsoimpervious to water, and maintaining a hydrostatic head of Water on thehydrocarbon be ing stored greater than the vapor pressure of 2 thehydrocarbon material at the temperature of the surrounding earth. Myinvention will be more particularly discussed and described inconnection with the accompanying drawing, which is a diagrammaticcross-sectional view, not drawn to scale, of one modification of myinvention.

Referring now to the drawing, a suitable hill, or mountain side, I0 islocated. At an elevated portion of this hill a water reservoir II isestablished. This may be either a natural orarticial reservoir. From alow point at the bottom of this reservoir a shaft I2 is sunk to asubstantial depth, If it is desired to store propane as a liquid thisshaft should be at least about 225 feet deep. From the side of the hillat an elevation of about, or slightly more than, 225 feet lower than theelevation of A the reservoir II, a horizontal tunnel I3 is driven intothe earth to a point which meets or closely approaches the bottom of theshaft I2. At the point where the shaft and the tunnel approach or meeteach other a large excavation is made, somewhat larger than the plannedvolume for the ilnal storage. Such an excavation, for example, may beroughly cylindrical in shape with a diameter of approximately 300 feetand a height of about 10 to 20 feet. The shaft I2 and the excavation I4are suitably lined, as with a layer of concrete I5 and a relatively thininner layer of corrosion-resistant steel I6. As will be readilyappreciated, neither of the linings I5 or I6, either jointly orindividually, needs to be strong enough to Withstand the vapor pressureof liquid propane, since they are mutually supported by the surroundingearth which will be sumciently strong to with` stand the pressure.

As will be readily appreciated the hill should be so chosen that it isnot far removed either from a source of supply for the propane to bestored, such as a reiinery or a natural gasoline plant, or so that itwill be not too far from a suitable distribution point. It will also bedesirable to choose a hill which has a relatively soft layer or stratumof rock at the point where it is desired to establishA the storage zone.Such a soft rock can be easily and relatively cheaply excavated but willstill have suiiicient structural strength to back up, and support, therelatively thin lining for the storage zone. Such a soft stratum may bechalk or soft sand stone.

In a preferred modiiication of my invention the shaft I2 has a suiicientdiameter that the interior 20, after the lining is in place, will belarge enough to enable a man to pass through it. At the point Where theshaft enters the storage 3 zone 2| it may be enlarged somewhat to form asmall room 22. The steel inner lining I6 has a hole in it at this pointwhich is normally covered with a cover 23. This cover will serve as apartition between storage zone 2| and the interior of shaft 20. Sincethis point will be at least about 225 feet below the surface of thewater in the reservoir I I when storing liquid propane, the shell I6 andthe cover 23 need not be stronger that is sufiicient to withstand aboutto 10 pounds per square inch differential pressure. Through this cover23 extends a relativelylarge conduit 24 down to the bottom of storagezone 2|. This conduit 24 `will be attached to the cover 23 by a flange25 so that it may be readily removed, leaving .a man hole through whichstorage zone 2| may be entered for purposes of inspection and/or repair.As will be readily appreciated, a separate man hole may be employed forthis purpose, with the conduit 24 being more permanently attached to theshell I 6, or to cover 23. n

A conduit 26 extends from the top of the storage zone 2| out throughtunnel I3. The liquid propane is introduced and withdrawn through thisconduit as desired. Flow through the conduit is controlled by valve 21.The conduit is preferably also equipped with an excess-flow valve 28, toprevent uncontrolled discharge from the tank in the event any of theexternal connections are broken. If desired, conduit 26 may be alsoequipped with an internal valve 30 which can be controlled from thebottom of the shaft 20, as by a control wheel 3|. It is generallydesirable also to have a conduit extending to the bottom of storage zone2| so that the entire storage zone may be drained of liquid material.'I'his latter conduit may comprise a valved extension 32 from conduit26, controlled also from the bottom of y shaft 20 by control Wheel 33.As will be readily appreciated, the propane conduit and the drainageconduit may be entirely separate conduits extending to the outsidethrough the tunnel I3, in which case internal valves 30 and 32 maybeunnecessary.

It is preferred that after the construction and lining of storage zone2I- has` been completed, and the desired conduits installed, the tunnelI3 be completely sealed, as by being plugged with concrete. Suchconcrete plugs 35 and 36 may be rmly anchored to the surrounding earth,in any suitable manner, so that they furnish a suciently strong backingtothe lining I6 vof theA storage zone 2|.

When the entire installation is complete, storage zone 2|, reservoir II,and the connecting conduit comprising shaft 20 and conduit pipe 24, maybe filled with water. Liquid propane can then be pumped in throughconduit 26 in any desired amount up to that which will justfail to bringthe water level down to the bottom of the conduit pipe 24. As the amountof liquid propane in storage varies, water will be supplied to orwithdrawn from reservoir I I through the connecting conduit. While itwill be preferable in many instances for reservoir II to have a volumeat least equal to the maximum volume of liquid propane to be stored instorage zone 2|, this is not absolutely necessary if there is availablea sufficient water supply to keep the reservoir water level at thenecessary height when large quantities of propane are withdrawn and ifthere is suitable overflow to remove excessive water whenlargequantities of propane are stored. It may be desirable to provide asuitable screen, or electrical barrier, to keep fish from going into 4shaft 20 and the bottom of storage zone 2|, as they may be killed by thesmall amount of hydrocarbons dissolved in the water, and also to preventsolid matter from accumulating on the bottom of the storage zone.

If at any time it becomes necessary to inspect the interior of storagezone 2 I, or to repair it, all the propane is withdrawn and then all thewater is withdrawn. In such a case it is not always necessary to emptyreservoir II, as a cofl'er dam may be built around the upper portion ofshaft 20, or a suitable extension may be attached which rises above thesurface of the water. It is, of course, necessary that shaft 20 andstorage zone 2| be emptied of water. In the modification shown finalremoval of water, after shaft 20 has been emptied, may be readilyeffected by closing valve SII-and opening valve 32. i

As will be readily appreciated the location of storage zone 2| should beso chosen that the temperature of the surrounding earth is notabnormally high, as it might be in the region of volcanic activity ornear hot springs. A diiference of elevation between the bottom of shaft20 and the surface of the water in reservoir II should be at least about225 feet when propane is stored as'a liquid, and with normalsubterranean temperatures. If one or more of the butanes is being storedas a liquid, or is present in substantial proportions in the propane,the vapor pressure of the liquid will be correspondingly lower and thedifference in elevation may be correspondingly less. While it ispossible to store ethane as a liquid in such a storage zone, with thedifference in elevation being at least about 1750 feet, this willgenerally be not practicable. However, it will often be desired to storea liquid hydrocarbon material containing a substantial quantity ofethane, in which instance the diIerence in elevation will need to beproportionally greater. In any event, it is necessary that thedifference in elevation be suiciently great to provide a hydrostatichead at least equivalent to the vapor pressure of the hydrocarbonmaterial being stored at the highest prevailing temperature of .theearth surrounding storage zone 2|. As will be appreciated propylene, orbutylenes, may also be contained in the hydrocarbon material beingstored. I

Various modifications of my invention may be practiced by one skilled inthe art without departing from the spirit, or scope, of the accompanyingdisclosure and without departing from the scope of the claims.

l. Means for storing as a liquid a normally gaseous hydrocarbon materialliqueiiable under pressure at normal earth temperatures which comprises,in combination, a totally enclosed subterranean storage zone, areservoir of water the surface of which is suillciently higher than saidstorage zone as to provide a hydrostatic head at least equal to theVapor pressure of said` hydrocarbon material at the highest prevailingtemperature of the earth surrounding. said storage zone, a verticalshaft connecting said reservoir and said storage zone, a partition atthe bottom of said shaft, a conduitl extending through said partition tothe bottom of said storage zone whereby water can freely ilow betweensaid reservoir and said storage zone, a man hole in said partition whichis normally closed, a conduit leading from the top of said storage zonefor introduction and removal of liquid hydrocarbon material and aconduit extending into the bottom of said storage zone for emptying ofsaid storage zone, a valve in each of the last said two conduits, andmeans connected with Veach said valve and operable from the bottom ofsaid shaft for opening and closing said valves,

2. Means for storing as a liquid a normally gaseous hydrocarbon materialliqueflable under pressure at normal earth temperatures which comprises,in combination, a totally enclosed subterranean storage zone, areservoir of water the surface of which is suiliciently higher than saidstorage zone as to provide a hydrostatic head at least equal to thevapor pressure of said hydrocarbon material at the highest prevailingtemperature of the earth surrounding said zone, a vertical shaftconnecting said reservoir and said storage zone, a partition at thebottom of said shaft, a conduit extending through said partition to thebottom of said storage zone whereby water can freely flow between saidreservoir and said storage zone, a man hole in said partition which isnormally closed, a conduit leading from the top of said storage zone forintroduction and removal of liquid hydrocarbon material and a conduitextending into the bottom of said storage zone for emptying of saidstorage zone.

3. Means for storing liquid propane which comprises, in combination, a.storage zone, a water reservoir directly above said storage zone at anelevation such that the water level is at least about 225 feet above thetop of said storage zone, a vertical conduit directly joining saidreservoir and the bottom of said storage zone and permitting free flowof water therebetween, and a horizontal conduit directly connecting withthe top of said storage zone for induction and eduction of propane.

4. Means for storing liquid C3 hydrocarbons Which comprises, incombination, a totally enclosed, subterranean storage zone, a reservoirof water the surface of which is at least about Y225 feet higher thanthe highest point of said storage zone, a conduit connecting saidreservoir and the bottom of said storage zone so constructed as topermit free tlow of water therebetween, and conduit means connectingwith the top of said storage zone for introduction and withdrawal ofliquid Ca hydrocarbons. i

ARTHUR N. KERR.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,006,912 Cook Oct. 24, 19111,008,830 Lamb et al. Nov. 14, 1911

